<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
     var arr=[1,2,3];
     arr.pop();//pop的作用是在数组后面删除一个数字
     alert(arr);
    </script>
</head>
<body>

</body>
</html>